cleanup(engine): remove redundant APIs (ooni#1536)

Let's just always use MaybeLookupLocationContext and
MaybeLookupBackendsContext. This change simplifies the interaction graph
related to using the probeservices and more generally the engine.

Part of ooni/probe#2700

cmd/ooniprobe/internal/cli/geoip/geoip.go

@@ -43,7 +43,7 @@ func dogeoip(config dogeoipconfig) error {
 	}
 	defer engine.Close()
 
-	err = engine.MaybeLookupLocation()
+	err = engine.MaybeLookupLocationContext(context.Background())
 	if err != nil {
 		return err
 	}

cmd/ooniprobe/internal/nettests/run.go

@@ -66,7 +66,7 @@ func RunGroup(config RunGroupConfig) error {
 	}
 	defer sess.Close()
 
-	err = sess.MaybeLookupLocation()
+	err = sess.MaybeLookupLocationContext(context.Background())
 	if err != nil {
 		log.WithError(err).Error("Failed to lookup the location of the probe")
 		return err
@@ -77,7 +77,7 @@ func RunGroup(config RunGroupConfig) error {
 		log.WithError(err).Error("Failed to create the network row")
 		return err
 	}
-	if err := sess.MaybeLookupBackends(); err != nil {
+	if err := sess.MaybeLookupBackendsContext(context.Background()); err != nil {
 		log.WithError(err).Errorf("Failed to discover OONI backends")
 		return err
 	}

cmd/ooniprobe/internal/ooni/ooni.go

@@ -42,7 +42,7 @@ type ProbeCLI interface {
 // ProbeEngine is an instance of the OONI Probe engine.
 type ProbeEngine interface {
 	Close() error
-	MaybeLookupLocation() error
+	MaybeLookupLocationContext(context.Context) error
 	ProbeASNString() string
 	ProbeCC() string
 	ProbeIP() string

cmd/ooniprobe/internal/oonitest/oonitest.go

@@ -84,7 +84,7 @@ func (eng *FakeProbeEngine) Close() error {
 }
 
 // MaybeLookupLocation implements ProbeEngine.MaybeLookupLocation
-func (eng *FakeProbeEngine) MaybeLookupLocation() error {
+func (eng *FakeProbeEngine) MaybeLookupLocationContext(_ context.Context) error {
 	return eng.FakeMaybeLookupLocation
 }
 

internal/engine/inputloader.go

@@ -146,7 +146,7 @@ func (il *InputLoader) loadOptional() ([]model.OOAPIURLInfo, error) {
 }
 
 // loadStrictlyRequired implements the InputStrictlyRequired policy.
-func (il *InputLoader) loadStrictlyRequired(ctx context.Context) ([]model.OOAPIURLInfo, error) {
+func (il *InputLoader) loadStrictlyRequired(_ context.Context) ([]model.OOAPIURLInfo, error) {
 	inputs, err := il.loadLocal()
 	if err != nil || len(inputs) > 0 {
 		return inputs, err
@@ -242,7 +242,7 @@ func staticInputForExperiment(name string) ([]model.OOAPIURLInfo, error) {
 }
 
 // loadOrStaticDefault implements the InputOrStaticDefault policy.
-func (il *InputLoader) loadOrStaticDefault(ctx context.Context) ([]model.OOAPIURLInfo, error) {
+func (il *InputLoader) loadOrStaticDefault(_ context.Context) ([]model.OOAPIURLInfo, error) {
 	inputs, err := il.loadLocal()
 	if err != nil || len(inputs) > 0 {
 		return inputs, err

internal/engine/session.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"net/url"
 	"os"
 	"sync"
@@ -155,7 +154,7 @@ func NewSession(ctx context.Context, config SessionConfig) (*Session, error) {
 	// use the temporary directory on the current system. This should
 	// work on Desktop. We tested that it did also work on iOS, but
 	// we have also seen on 2020-06-10 that it does not work on Android.
-	tempDir, err := ioutil.TempDir(config.TempDir, "ooniengine")
+	tempDir, err := os.MkdirTemp(config.TempDir, "ooniengine")
 	if err != nil {
 		return nil, err
 	}
@@ -384,16 +383,6 @@ func (s *Session) Logger() model.Logger {
 	return s.logger
 }
 
-// MaybeLookupLocation is a caching location lookup call.
-func (s *Session) MaybeLookupLocation() error {
-	return s.MaybeLookupLocationContext(context.Background())
-}
-
-// MaybeLookupBackends is a caching OONI backends lookup call.
-func (s *Session) MaybeLookupBackends() error {
-	return s.MaybeLookupBackendsContext(context.Background())
-}
-
 // ErrAlreadyUsingProxy indicates that we cannot create a tunnel with
 // a specific name because we already configured a proxy.
 var ErrAlreadyUsingProxy = errors.New(

internal/engine/session_integration_test.go

@@ -146,7 +146,7 @@ func newSessionForTestingNoLookups(t *testing.T) *Session {
 
 func newSessionForTestingNoBackendsLookup(t *testing.T) *Session {
 	sess := newSessionForTestingNoLookups(t)
-	if err := sess.MaybeLookupLocation(); err != nil {
+	if err := sess.MaybeLookupLocationContext(context.Background()); err != nil {
 		t.Fatal(err)
 	}
 	log.Infof("Platform: %s", sess.Platform())
@@ -164,7 +164,7 @@ func newSessionForTestingNoBackendsLookup(t *testing.T) *Session {
 
 func newSessionForTesting(t *testing.T) *Session {
 	sess := newSessionForTestingNoBackendsLookup(t)
-	if err := sess.MaybeLookupBackends(); err != nil {
+	if err := sess.MaybeLookupBackendsContext(context.Background()); err != nil {
 		t.Fatal(err)
 	}
 	return sess
@@ -245,7 +245,7 @@ func TestBouncerError(t *testing.T) {
 	if sess.ProxyURL() == nil {
 		t.Fatal("expected to see explicit proxy here")
 	}
-	if err := sess.MaybeLookupBackends(); err == nil {
+	if err := sess.MaybeLookupBackendsContext(context.Background()); err == nil {
 		t.Fatal("expected an error here")
 	}
 }
@@ -260,7 +260,7 @@ func TestMaybeLookupBackendsNewClientError(t *testing.T) {
 		Address: "httpo://jehhrikjjqrlpufu.onion",
 	}}
 	defer sess.Close()
-	err := sess.MaybeLookupBackends()
+	err := sess.MaybeLookupBackendsContext(context.Background())
 	if !errors.Is(err, ErrAllProbeServicesFailed) {
 		t.Fatal("not the error we expected")
 	}
@@ -272,7 +272,7 @@ func TestSessionLocationLookup(t *testing.T) {
 	}
 	sess := newSessionForTestingNoLookups(t)
 	defer sess.Close()
-	if err := sess.MaybeLookupLocation(); err != nil {
+	if err := sess.MaybeLookupLocationContext(context.Background()); err != nil {
 		t.Fatal(err)
 	}
 	if sess.ProbeASNString() == model.DefaultProbeASNString {
@@ -419,7 +419,7 @@ func TestAllProbeServicesUnsupported(t *testing.T) {
 		Address: "mascetti",
 		Type:    "antani",
 	})
-	err = sess.MaybeLookupBackends()
+	err = sess.MaybeLookupBackendsContext(context.Background())
 	if !errors.Is(err, ErrAllProbeServicesFailed) {
 		t.Fatal("unexpected error")
 	}

internal/experiment/webconnectivity/webconnectivity_test.go

@@ -236,11 +236,11 @@ func newsession(t *testing.T, lookupBackends bool) model.ExperimentSession {
 		t.Fatal(err)
 	}
 	if lookupBackends {
-		if err := sess.MaybeLookupBackends(); err != nil {
+		if err := sess.MaybeLookupBackendsContext(context.Background()); err != nil {
 			t.Fatal(err)
 		}
 	}
-	if err := sess.MaybeLookupLocation(); err != nil {
+	if err := sess.MaybeLookupLocationContext(context.Background()); err != nil {
 		t.Fatal(err)
 	}
 	return sess